Conventionally, in a HIT solar cell module, bus bar electrodes 20 of a plurality of solar cells are electrically connected to each other by wiring members 40 made of a conductive material such as copper foil, as shown in FIG. 1. The plurality of solar cells are sealed in a translucent sealing member made of EVA or the like between a translucent front surface protection member and a back surface protection member. The front surface protection member is made of glass, translucent plastic or the like. The back surface protection member is a film of polyethylene terephthalate (PET) or the like.
In manufacturing the solar cells, bus bar electrodes 20 and finger electrodes 30 are formed on surfaces of each photoelectric conversion body 10 by use of a conductive paste. Then, in general, wiring members 40 are solder-bonded on the bus bar electrodes 20 to connect the solar cells in series (see, for example, Japanese Patent Publication No. 2005-217148).
How to perform the soldering will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view taken along the line A-A of FIG. 1.
Each wiring member 40 is made of a metal material, such as copper foil, completely coated with a solder plating 90 in advance. When the wiring member 40 is soldered to the bus bar electrode 20 made of a silver paste, flux is applied to any of a surface of the bus bar electrode 20 and a surface, which faces a solar cell, of the wiring member 40. Then, the wiring member 40 is provided on the surface of the bus bar electrode 20, and heated. In this heating, the wiring member 40 is soldered to be fixed to the bus bar electrode 20 by alloying a solder portion of the wiring member 40 and the silver paste to form an alloy layer 50 while removing an oxide layer on the surface of the bus bar electrode 20 by using the flux.